DE112012007010B4 - Vehicle with a machine and a motor that can generate a starting torque - Google Patents

Abstract

A vehicle comprising: a machine; a motor that can generate a cranking torque that is applied to a rotary shaft of the engine; and a controller that controls the engine such that the cranking torque becomes a target torque when a start request of the engine is issued; wherein, when the start request is issued during a coasting operation of the engine, the control device sets the target torque when a rotational speed of the engine is higher than a threshold rotational speed to be lower than the target torque when the rotational speed is lower than the threshold rotational speed, and the threshold speed is a value corresponding to a lower limit of a speed range in which a misfire of the engine occurs in a state where an amount of intake air to the engine is less than a predetermined amount.

Description

TECHNICAL AREA

The present invention relates to a vehicle having a machine and a motor that can generate cranking torque.

STATE OF THE ART

JP 2004-92623 A (PTD 1) discloses that restarting a machine is allowed when a throttle position is smaller than a predetermined value in a state where the engine is stopped, while running the vehicle, and restarting the engine is allowed after the throttle position has been forcibly reduced to the predetermined value. This prevents an occurrence of sudden acceleration due to abruptly increasing a driving force at the time of restarting the engine while allowing the engine to be restarted while driving the vehicle.

DE 10 2011 005 469 A1 discloses a method for transferring a piston engine of a vehicle driveline from an off-mode to a powered-on state. An electric machine can be brought into operative connection with the reciprocating internal combustion engine via a switching element designed with infinitely variable transmissibility. When the reciprocating internal combustion engine is switched off, a starting torque for starting the reciprocating internal combustion engine to be provided by the electric machine is determined as a function of a current operating state of the reciprocating internal combustion engine and an initial starting value of the transmission capacity of the switching element to which the transmission capability of the switching element for guiding the starting torque of the electric Machine is at least set in the direction of the piston internal combustion engine. During a first phase of the starting process of the reciprocating internal combustion engine, the transmission capability of the switching element is brought to an intermediate value which is smaller than the starting value by an offset value and to the starting value during a second phase of the starting process of the reciprocating internal combustion engine, wherein the gradient of the change of the transmission capability of the switching element during the first phase is greater than the gradient during the second phase.

DE 10 2010 034 554 A1 also relates to a system and method for restarting an engine.

SUMMARY OF THE INVENTION

TECHNICAL PROBLEM

However, the engine may not be properly restarted if the engine is restarted in a state in which, during a coasting operation of the engine (while the engine is rotating by inertia), the throttle position is small (the amount of intake air is small) such as in PTD 1. For example, even if restarting the engine by injecting fuel from an injector during rotation of the engine at a high rotational speed is attempted in the state where the amount of intake air is small, as in PTD 1 , the amount of fuel becomes excessively large in the amount of intake air, which may cause misfires.

As a measure, the amount of fuel injected from the injector can be reduced. However, even if the amount of injected fuel is reduced to a minimum value, occurrence of misfires can not be avoided if the amount of the fuel is still excessively large in the amount of intake air. As another possible measure, the amount of intake air can be increased. With this measure, however, an abrupt increase in a driving force at the time of restarting the engine (the problem solved in PTD 1) can not be avoided.

The present invention has been made to solve the above-described problem, and an object of the invention is to maintain the engine speed within a speed range in which misfires without an increase in the amount of intake air at the time of starting the engine during a coasting operation are avoided can be.

THE SOLUTION OF THE PROBLEM

A vehicle according to this invention includes an engine, a motor that can generate cranking torque applied to a rotating shaft of the engine, and a control device that controls the engine such that the cranking torque becomes a target torque when a start request of the engine is issued. The control device changes the target torque in accordance with a rotational speed of the engine when the start request is issued during a coasting operation of the engine.

Preferably, the control device sets the target torque when the rotational speed is higher than a threshold rotational speed to be a value lower than the target torque when the rotational speed is lower than the threshold speed. The threshold speed is a value corresponding to a lower limit of a rotation range in which misfires of the engine occur in a state where an amount of intake air to the engine is less than a predetermined amount.

Preferably, the controller adjusts the target torque when the rotational speed is higher than the threshold rotational speed to be a value that decreases as the rotational speed increases.

Preferably, the target torque is set to a value at which the rotational speed can be reduced to a rotational range in which a misfire of the engine can be avoided in a state where the amount of intake air to the engine is less than the predetermined amount.

Preferably, the target torque is set to a value at which the rotational speed is reduced to the rotational range in which a misfire of the engine can be avoided, and in which the rotational speed can be maintained in a rotational range in which a resonance of the vehicle can be avoided.

Preferably, the controller changes the target torque in accordance with the rotational speed when the start request is issued during a coasting operation of the engine in the state where the amount of intake air to the engine is less than the predetermined amount.

Preferably, the controller changes the cranking torque based on the rotational speed when the starting request is issued during processing for stopping the engine while the vehicle is running.

Preferably, the control device changes the cranking torque based on the rotational speed when the starting request is issued during a coasting operation of the engine in a state where an operation amount of an accelerator pedal by an operator is smaller than a predetermined amount.

Preferably, the control device sets the target torque to a value that does not vary in accordance with the rotational speed when the start request is issued while the engine is not rotating.

ADVANTAGEOUS EFFECTS OF THE INVENTION

In accordance with the present invention, the rotational speed of the engine in a rotational speed range in which a misfire can be avoided without increasing the amount of intake air at the time of starting the engine during a coasting operation can be maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is an overall block diagram of a vehicle.

2 is a nomographic chart showing a case where the engine is started while the vehicle is traveling in a forward direction.

3 FIG. 10 is a nomographic chart showing a case where the engine is started during engine stop processing. FIG.

4 FIG. 14 is a (first) flowchart showing a processing procedure executed by an ECU.

5 FIG. 15 is a graph showing a correlation between a target cranking torque TCtag and an engine speed Ne.

6 FIG. 14 is a time chart of engine speed Ne and cranking torque TC.

7 Fig. 10 is a (second) flowchart showing a processing procedure executed by the ECU.

8th FIG. 14 is a (third) flowchart showing a processing procedure executed by the ECU.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described hereinafter with reference to the drawings. In the following description, the same components are denoted by the same symbols. The names and functions of these are also the same. A detailed description of these will therefore not be repeated.

1 is an overall block diagram of a vehicle 1 according to this embodiment. vehicle 1 includes a drive device that generates a vehicle drive force and an ECU (Electronic Control Unit) 1000 on which a variety of devices of the vehicle 1 including the drive device controls.

The driving device of the vehicle 1 has a machine 100 , a first MG (MG: motor generator) 200 , a power sharing device 300 , a second MG 400 , a drive shaft (Output shaft) 560 , a PCU (power control unit) 600 , a battery 700 and a SMR (system main relay) 710 on.

The vehicle 1 is a hybrid vehicle that travels with a driving force from at least one of a machine 100 and a second MG 400 is issued. The vehicle to which the present invention is applied is not limited to a hybrid vehicle, and may be, for example, a vehicle using only the engine as a driving force source.

The machine 100 is an internal combustion engine that outputs a motive force by burning fuel. The motive power or motive power of the machine 100 is applied to the power sharing device 300 via a damping mechanism 101 transfer. The damping mechanism 101 absorbs and reduces variations in rotation associated with the power split device 300 from the machine 100 is transmitted.

The power splitting device 300 divides the power of movement or force generated by the machine 100 is entered, in a motive power or force on the drive shaft 560 and a motive power on the first MG 200 on.

The power sharing device 300 is a planetary gear mechanism with a sun gear (S) 310 a ring gear (R) 320 , Pinions or pinion gears (P) 340 that with the sun wheel (S) 310 and the ring gear (R) 320 interlocked, and a carrier (C) 330 of the pinion gears (P) 340 rotatably holds such that the pinion gears are also rotatable about the sun gear. The carrier (C) 330 is with a crankshaft of the machine 100 connected. The sun wheel (S) 310 is with a rotor of the first MG and the first motor generator 200 connected. The ring gear (R) 320 is with the output wave 560 connected.

With the construction of the power sharing device 300 , as described above, have a speed of the sun gear (S) 310 (= first MG rotational speed Nm1), a rotational speed of the carrier (C) 330 (= Engine speed Ne) and a speed of the ring gear (R) 320 (= second MG speed Nm2, ie, a vehicle speed V) has a relationship such that it is represented by straight lines on the nomographic chart of the power split device 300 (please refer 2 and 3 which are described below), ie, a relationship such that if any two of the speeds are determined, the remaining speed is also determined.

Everyone from the first MG 200 and the second MG 400 is a rotating electric AC machine and serves as a motor as well as a generator. A rotor of the second MG 400 is with the output wave 560 connected. As will be described below, the first MG generates 200 at the time of starting the machine 100 a torque (hereinafter referred to as a "cranking torque TC") applied to a rotating shaft (crankshaft) of the engine 100 is applied to the machine 100 to start.

The output wave 560 is characterized by at least one of the engine's power 100 via the power transmission device 300 is transmitted, and the motive power of the second MG 400 turned. The torque of the output shaft 560 is attached to a left and a right drive wheel 82 via a reduction or reduction gear 81 transfer. This causes the vehicle 1 to drive.

The PCU 600 Converts high voltage DC power from a battery 700 is supplied to an AC current for output to the first MG or motor generator 200 and / or the second MG or motor generator 400 , This causes the first MG 200 and / or the second MG 400 to be driven. The PCU 600 also converts AC power passing through the first MG 200 and / or the second MG 400 is generated in DC power for output to the battery 700 , This causes the battery 700 to be loaded.

The battery 700 is a secondary battery, the high voltage (about 200 V, for example) DC power to drive the first MG 200 and / or the second MG 400 stores. The battery 700 typically includes a nickel metal hydride battery or a lithium ion battery. The vehicle 1 In addition, it may have a system mounted on it which is the battery 700 allows with electrical power or current from a power supply outside the vehicle 1 to be loaded.

The SMR or system main relay 710 is a relay for switching a connection state between the battery 700 and the electrical system including PCU 600 ,

The vehicle 1 also has an engine speed sensor 10 , an air flow meter 11 , a throttle position sensor 12 , an output shaft speed sensor 15 , Resolver or resolver 21 . 22 and an accelerator position sensor 31 on. The engine speed sensor 10 detects the engine speed Ne. The air flow meter 11 detects a lot of intake air Ga (a lot of air entering the machine 100 is pulled). The throttle position sensor 12 detects a throttle position θ (An operation amount of a throttle valve). The output shaft speed sensor 15 detects a rotational speed Np of the output shaft 560 as a vehicle speed V. resolver 21 and 22 detect a first MG speed Nm1 and a second MG speed Nm2, respectively. The accelerator position sensor 31 detects an operation amount AP of an accelerator pedal by an operator. Each of these sensors gives the detection result to the ECU 1000 out.

The vehicle 1 also has a start switch 35 on. The start switch 35 is a switch for an operator to switch a control state of the control system (hereinafter simply referred to as the "vehicle system") of the vehicle 1 including the drive device request. If the user or the operator the start switch 35 presses, gives the start switch 35 a signal R, pressing the start switch 35 indicates to the ECU 1000 out.

The ECU 1000 includes a not-shown CPU (Central Processing Unit) and a memory, and executes a predetermined operation processing based on information stored in the memory and information from the various sensors. The ECU 1000 controls the vehicle system based on results of the operation processing.

The ECU 1000 switches the control state to any one of an activated state (hereinafter referred to as the "ready-on state") and a stopped state (hereinafter referred to as the "ready-off state") based on a signal R from the start switch 35 around.

If the user or the operator the start switch 35 in the Ready-ON state (hereinafter referred to as the "Ready-OFF requesting operation"), the ECU causes 1000 the machine 100 by stopping the fuel injection to the engine 100 to stop (hereafter referred to as the "engine stop processing") and switches the control state of the vehicle system to the ready-off state and the ready-off state, respectively. The machine 100 , the first motor generator or MG 200 and the second motor generator or MG 400 are stopped in the ready-OFF state, so that even when the operator operates the accelerator pedal, no driving force is generated from the driving device.

When the operator releases the start switch 35 In the Ready-OFF state (hereinafter referred to as the "Ready-ON request operation"), the ECU will leave 1000 the machine 100 to the machine 100 (hereinafter referred to as the "engine start processing") and switches the control state of the vehicle system to the ready ON state and the ready ON state after the engine start processing is completed. In the ready-on state is an operation of the machine 100 , the first MG 200 and the second MG 400 and a driving force is generated by the driving device in accordance with the operation of the accelerator pedal by the operator.

2 shows a nomographic diagram of the case in which the machine 100 is started while the vehicle is traveling in a forward direction. As in 2 is shown, the ECU generates 1000 a torque in a positive direction from the first MG 200 , whereby a starting torque TC in the positive direction to the crankshaft of the machine 100 is applied. In this case, when the first MG rotational speed Nm1 is a positive value, the ECU controls 1000 the first MG 200 in a power running state, whereby a torque in a positive direction from the first MG or motor generator 200 is produced. Conversely, when the first MG speed Nm1 is a negative value, the ECU controls 1000 the first MG 200 in a regenerative state, whereby a torque in the positive direction of the first MG 200 is produced.

Once the engine speed Ne has reached a predetermined speed range due to the cranking torque TC, the ECU performs 1000 a controller such that a fuel injector supplies fuel to the engine 100 injects and an igniter ignites the injected fuel. This puts the combustion of fuel in a complete state (namely, a complete explosion is achieved), completing the engine start processing.

In the vehicle 1 With the structure described above, there are various cases in which a request to start the engine is issued during the engine stop processing (when the fuel injection is stopped, but the engine 100 still in overrun mode). For example, as described above, when the ready-off requesting operation is made while the vehicle is running, the engine stop processing is started. When the ready-ON requesting operation is made during the machine stop processing, the request to start the machine is issued. Further, the request to start the engine may also be issued if, for some reason, the operator is pedaling of the accelerator pedal stops and requires the engine brake or engine braking while the engine stop processing is being performed.

The ECU 1000 According to this embodiment brings a starting torque TC on the machine 100 not only only when the request to start the engine is issued while the engine is stopped (if the engine 100 does not rotate), but also when the request to start the engine is issued during the engine stop processing (when the engine 100 in overrun mode).

However, if the engine speed Ne at the time of restarting the engine 100 During engine stop processing is high, there is a possibility that a misfire may occur and the engine 100 can not be restarted. That is, in a region where an engine speed Ne is high, if the intake air amount is small, the amount of injected fuel becomes excessively large in the intake air amount, causing a misfire without combustion of the fuel. Therefore, there is a possibility that the machine 100 in a region where the engine speed Ne is high, can not be restarted.

3 shows a nomographic diagram of the case in which the machine 100 during the machine stop processing is started.

In 3 "α" is a value corresponding to an engine speed at which the engine misfires 100 starts to occur, in a state where the amount of intake air Ga is smaller than the predetermined amount. This value "α" will hereafter be referred to as "threshold speed α", an engine speed range higher than the threshold speed α will be referred to as the "misfire range" and an engine speed range lower than the threshold speed α will be referred to as the "misfire avoidance range". The threshold speed α is a value corresponding to a lower limit value of the misfire region. In this embodiment, a threshold speed α is found in advance through experiments or the like, assuming a case where the amount of intake air Ga is a minimum value (a case where the throttle valve is fully closed).

In 3 "β" (β <α) is a value corresponding to an upper limit of an engine speed range in which a resonance of the damper mechanism 101 can occur. This value "β" will hereafter be referred to as "threshold speed β", an engine speed range lower than the threshold value β will be referred to as the "resonance range" and an engine speed range higher than the threshold speed β will be referred to as the "resonance avoidance range". Further, an engine speed range higher than the threshold value β and lower than the threshold value α will be referred to as the "optimum range".

As in 3 12, it is assumed that the engine stop processing is started in a state represented by a collinear line L1 (a state in which the engine speed Ne is above the threshold speed α). In this case, when the fuel injection is stopped, the engine speed Ne gradually decreases to zero. When the request to start the engine is issued during such a coasting operation of the engine, a cranking torque TC is applied.

If the cranking torque TC is excessively large, the engine speed Ne increases further than before cranking, and enters the misfire area as indicated by a collinear line L2. Therefore, there is a possibility that a complete explosion of the machine 100 can not be achieved.

On the other hand, if the cranking torque TC is excessively small, the engine rotational speed Ne decreases too much and remains in the resonance range as represented by a collinear line L3, which may cause the generation of vibration or noise.

That is why in the ECU 1000 According to this embodiment, when the request to start the engine is issued during the engine stop processing (during a coasting operation of the engine), a target value of the cranking torque TC (hereinafter referred to as "cranking target torque TCtag") is changed to an appropriate value in accordance with the engine speed Ne, so that the engine speed Ne is reduced to and remains in the optimum range during cranking, as shown by a collinear line L4.

As another method for avoiding misfire, the amount of injected fuel may be reduced. However, the minimum value of injected fuel is determined physically by the specifications of the fuel injector (the shortest time during which the fuel injector nozzle can be opened and closed), and therefore misfire can not be avoided if the amount of fuel is still excessively large even if the amount of injected fuel is at a limit, namely a minimum value, is reduced. Further, if only the prevention of misfire is desired, the amount of intake air Ga can be increased. If an amount of intake air Ga is increased, however, the driving force abruptly increases at the time of restarting the engine, causing a sudden acceleration of the vehicle. This feeling of acceleration can often be undesirable to an operator wishing to stably propel the vehicle after the engine is restarted or to an operator wishing to initiate the operation of engine braking. Therefore, it is not desirable to increase the amount of intake air Ga when the engine is restarted during the engine stop processing. In view of the foregoing, the ECU changes 1000 According to this embodiment, the cranking target torque TCtag is set to an appropriate value in accordance with the engine speed Ne, so that the engine speed Ne is reduced to and remains at the optimum range during cranking without increasing the amount of intake air Ga.

4 FIG. 10 is a flowchart showing a processing procedure executed by the ECU. FIG 1000 is performed. The procedure in this flowchart is repeatedly executed in a predetermined cycle.

In step ("step" hereinafter abbreviated as "S") 10 determines the ECU 1000 Whether the request to start the machine has been issued or not. If the request to start the engine has not been issued (NO in S10), the ECU stops 1000 the processing.

When the request to start the engine has been issued (YES in S10), the ECU shifts 1000 the processing to S11 where it is determined whether the engine speed Ne is greater than zero or not. This processing is for determining whether or not the engine is under coasting during the engine stop processing.

When the engine speed Ne is zero (NO in S11), ie the engine 100 does not turn, puts the ECU 1000 the processing to S13 where it sets the cranking target torque TCtag to a predetermined value T1. This processing corresponds to a case where the starting target torque TCtag is set using a conventional technique. This embodiment describes an exemplary case in which a predetermined value T1 is a fixed value that does not change in accordance with the engine speed Ne.

On the other hand, when the engine speed Ne is greater than zero (YES in S11), that is, the engine is in overrun during the engine stop processing, the ECU is offset 1000 the processing to S12 where it changes the cranking target torque TCtag in accordance with the engine speed Ne. In other words, the ECU 1000 the target target torque TCtag to the function f (Ne) having the engine speed Ne as a parameter.

5 FIG. 15 is a graph showing a correlation between the cranking target torque TCtag and a engine rotational speed Ne set by the processing in FIG. 512.

As in 5 is shown, the cranking target torque TCtag in the misfire region (engine speed region higher than the threshold revolution speed α) is set to a value lower than the cranking target torque TCtag in the misfire prevention region (engine revolution speed region lower than the threshold revolution speed α).

The starting target torque TCtag in the misfire area is set to a value that decreases as the engine speed Ne increases. On the other hand, the target target torque TCtag in the misfire avoidance area is set to a predetermined value T1 which is the same as the value where Ne = 0 in a speed range near zero. In a rotation range near the threshold speed α, the cranking target torque TCtag gradually decreases below the predetermined value T1 as it approaches the threshold speed α.

The starting target torque TCtag, which in 5 is set to a value at which the engine speed Ne toward the misfire avoidance area can be reduced (engine speed range lower than the threshold speed α) and can be maintained in the resonance avoidance area (engine speed range higher than the threshold speed β).

In this way, a suitable cranking torque TC with a good balance with engine friction in the optimum range (engine speed range lower than the threshold speed α and higher than the threshold speed β) can be applied to the engine 100 be applied. For example, when an engine speed Ne before startup is higher than the threshold speed α, a cranking torque TC may be decreased in accordance with the engine speed Ne, so that the engine speed Ne is reduced toward the optimum range at an early time during cranking and remains in the optimum range. This allows the machine 100 to be properly started while avoiding misfire and resonance.

Returning to 4 leads the ECU 1000 processing to generate a cranking torque TC in S14. In particular, the ECU controls 1000 the first motor generator or MG 200 such that the actual cranking torque TC becomes the cranking target torque TCtag set in S12 or S13.

In S15, the ECU determines 1000 Whether or not the engine speed Ne is in the optimum range (engine speed range lower than the threshold speed α and higher than the threshold speed β). When the engine speed Ne is not in the optimum range (NO in S15), the ECU returns 1000 with the processing back to S14.

If the engine speed Ne is in the optimum range, YES in S15), the ECU shifts 1000 the processing to S16 where it performs a control such that fuel to the engine 100 is injected for ignition. This completes the engine startup processing.

6 FIG. 15 is a time chart of an engine speed Ne and a cranking torque TC when the request to start the engine is issued during the engine stop processing.

If the engine stop processing is started at a time t1 when the vehicle 1 in a state in which the engine speed Ne is higher than the threshold speed α, the engine speed Ne gradually decreases toward zero.

If the request to start the machine is issued at a time t2 when the machine 100 is in overrun, the starting target torque TCtag is set to an optimum value in accordance with the engine speed Ne (see FIG 5 which has been described above). The actual cranking torque TC is then controlled to become the cranking target torque TCtag. This causes the engine speed Ne to decrease from the misfire area to the optimum area. Since the starting torque TC and the engine friction torque in the optimum range are balanced with each other, the engine speed Ne remains in the optimum range without decreasing to the resonance range. Then, at time t3, when the engine speed Ne remains in the optimum range, fuel becomes the engine 100 injected and ignited what the machine 100 causes to be properly started (complete explosion) while avoiding misfire and resonance.

Usually, it has not been considered that the engine is started in a state where the engine is higher than the threshold speed α in the overrun operation in an engine speed range. Therefore, as indicated by the dashed line in 6 For example, if there are some cases in which, even though the engine is in coasting, the predetermined value T1, which is the same as the value when the engine is not rotating, is set as the cranking target torque TCtag. In this case, the cranking torque TC becomes excessively large, and the engine speed Ne enters the misfire range during cranking, which may cause a misfire. Alternatively, as indicated by the double-dotted chain line in 6 For example, when the engine is started during a coasting operation of the engine, there are other cases where the cranking torque TC is generated at the first position (TCtag = 0). In this case, the engine speed Ne decreases too much and enters the resonance range, which may cause generation of vibration or noise at the time of starting the engine. In this embodiment, the engine can be started properly without causing these problems.

As described above, when the request to start the engine is issued during a coasting operation of the engine, the ECU changes 1000 According to this embodiment, the cranking target torque TCtag in accordance with the engine speed Ne. Therefore, even when the engine is started in a state where the engine speed Ne is high and an amount of intake air Ga is small, the engine speed Ne during cranking can be reduced favorably to the speed range in which misfire can be avoided and remain there without increasing the amount of intake air Ga.

<First modification>

In the flowchart that is in 4 is shown, which has been described above, in which the request for starting the engine has been issued (YES in S10) and the engine speed Ne is greater than zero (YES in S11), the starting target torque TCtag is changed in accordance with the engine speed Ne (S12 ).

In contrast, at least one of the following additional conditions may be 1 to 3 below Need to be added as a condition for changing the cranking target torque TCtag in accordance with the engine speed Ne.

(Additional Condition 1) The engine stop processing is executed while the vehicle is running.

(Additional Condition 2) The amount of intake air Ga is smaller than a predetermined amount G0.

(Additional Condition 3) An operation amount AP of the accelerator pedal is smaller than a predetermined amount A0.

7 FIG. 10 is a flowchart showing an example of a processing procedure executed by the ECU 1000 is carried out according to a first modification. In the flowchart that is in 7 4, the processings in S20, S21 and S22 have been added according to the above-mentioned additional conditions 1 to 3, corresponding to the flowchart shown in FIG 4 is shown, which is described above.

That is, the ECU 1000 changes the cranking target torque TCtag in accordance with the engine speed Ne when the request to start the engine is issued (YES in S10), the engine stop processing is performed while the vehicle is running (YES in S20), the engine speed Ne is greater than zero (YES in S11), the amount of intake air Ga is less than a predetermined amount G0 (YES in S21), and the operation amount AP of the accelerator pedal is smaller than a predetermined amount A0 (YES in S22). If not (NO in any one of S10, S11 and S20 to S22), the ECU shifts 1000 the processing to S13 where it sets the cranking target torque TCtag to a predetermined value T1.

In this way, the cranking target torque TCtag can be changed in accordance with the engine rotational speed Ne only when the possibility of a misfire is high.

<Second modification>

8th FIG. 12 is a flowchart showing an example of a processing procedure performed by the ECU 1000 is carried out according to a second modification. It should be noted that these steps are taken in 8th shown by the same numbers as the numbers of the previously described steps in FIG 4 are already described, and therefore a detailed description of them will not be repeated herein.

The ECU 1000 determines in S30 whether the engine start processing is performed or not. If the request to start the machine has been issued or the complete explosion of the machine 100 has not been reached after the request to start the machine, the ECU determined 1000 in that the engine start processing is performed. When the engine start processing is not performed (NO in S30), the ECU completes or completes 1000 the processing.

On the other hand, when the engine start processing is performed (YES in S30), the ECU shifts 1000 the processing to S31 where it determines whether or not the engine rotational speed Ne is greater than the threshold rotational speed α described above. This processing is for determining whether or not the engine rotational speed Ne is included in the above-described misfire region.

When the engine speed Ne is smaller than the threshold speed α (NO in S31), the ECU shifts 1000 the processing to S33 where it sets the starting target torque TCtag to a predetermined value A. This processing corresponds to a case where the starting target torque TCtag is set using a conventional technique. For example, the predetermined value A is set to a value similar to the starting target torque TCtag in the misfire prevention area, which is shown in FIG 5 is shown, which is described above.

When the engine speed Ne is greater than the threshold speed α (YES in S31), the ECU shifts 1000 the processing to S32 where it sets the starting target torque TCtag to a predetermined value B. The predetermined value B herein is a value that varies in accordance with the engine speed Ne, and is smaller than a predetermined value A set in S33. For example, the predetermined value B is set to a value similar to the cranking target torque TCtag in the misfire range shown in FIG 5 is shown, which is described above.

In S34, the ECU controls 1000 the first motor generator or MG 200 such that the actual cranking torque TC becomes the cranking target torque TCtag set in S32 or S33.

In S35, the ECU determines 1000 Whether or not the engine speed Ne is included in the optimum range (engine speed range lower than the threshold speed α and higher than the threshold speed β).

If the engine speed Ne is not included in the optimum range (NO in S35), the ECU returns 1000 the processing returns to S31 and repeats the processing from S31 to S34.

If the engine speed Ne is included in the optimum range (YES in S35), the ECU shifts 1000 the processing to S16 where it performs a control such that fuel to the engine 100 is injected for ignition. This completes the engine start processing.

Also in this way, the engine speed Ne during cranking can be favorably reduced to and maintained at the speed range in which misfire can be avoided without increasing the amount of intake air Ga, as in the first embodiment.

It should be understood that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms in the claims.

LIST OF REFERENCE NUMBERS

• 1 : Vehicle; 10 : Engine speed sensor; 11 : Air flow meter; 12 : Throttle position sensor; 15 : Output shaft speed sensor; 21 . 22 : Resolver or resolver; 31 : Accelerator position sensor; 35 : Start switch; 81 : Reduction gear; 82 : Drive wheel; 100 : Machine; 101 : Damping mechanism; 200 : first motor generator; 300 : Power sharing device; 400 : second motor generator; 560 : Output wave; 600 : PCU; 700 : Battery; 1000 : ECU

Claims (7)

Vehicle that has: a machine; a motor that can generate a cranking torque that is applied to a rotary shaft of the engine; and a control device that controls the engine such that the cranking torque becomes a target torque when a start request of the engine is issued; wherein, when the start request is issued during a coasting operation of the engine, the control device sets the target torque when a rotational speed of the engine is higher than a threshold rotational speed to be lower than the target torque when the rotational speed is lower than the threshold rotational speed, and the threshold speed is a value corresponding to a lower limit of a speed range in which a misfire of the engine occurs in a state where an amount of intake air to the engine is less than a predetermined amount. The vehicle of claim 1, wherein the controller adjusts the target torque when the rotational speed is higher than the threshold rotational speed to be a value that decreases as the rotational speed increases. A vehicle according to claim 1 or 2, wherein the target torque is set to a value at which the rotational speed can be reduced to a rotational speed range in which a misfire of the engine can be avoided in a state where an amount of intake air to the engine is smaller as a predetermined amount. A vehicle according to any one of claims 1 to 3, wherein the target torque is set to a value at which the rotational speed can be reduced to the rotational speed range in which engine misfire can be avoided and the rotational speed can be maintained in a rotational speed region in which a resonance of the vehicle can be avoided. The vehicle according to any one of claims 1 to 4, wherein the control device changes the target torque in accordance with the rotational speed when the start request is issued during a coasting operation of the engine in a state where an amount of intake air to the engine is less than a predetermined amount , The vehicle according to any one of claims 1 to 5, wherein the control device changes the target torque based on the rotational speed when the start request is issued during processing for stopping the engine while the vehicle is running. The vehicle according to one of claims 1 to 6, wherein the control device sets the target torque to a value that does not change in accordance with the rotational speed when the start request is issued while the engine is not rotating.

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